Copolymers of 3,4 or 3,5-dichloro alpha methyl-styrene with fluoroethylenes



Patented Apr. 10, 1951 coPoLYMERs F 3,4 0R as-nlonnono ALPHAMETHYL-STYRENE WITH FLUORO- ETHYLENES Theodore A. Te Grotenhuis, OlmstedFalls, and. Gilbert H. Swart, Akron,'0hio, assignors to The General Tireand Rubber Company, Akron, Ohio, a corporation of Ohio No Drawing.Application August 28, 1946,

Serial No. 693,586

7 Claims. I

This invention relates to resinous copolymers of nuclearlypolyhalogenated alpha-alkylarylvinyl compounds and to a method ofpreparing the same.

It is known that dichlorostyrenes such as thel-vinyl-2,4-dichlorobenzene and the l-vinyl- 2,5-dichlorobenzene, andothers, may be polymerized and copolymerized to produce rubbers orresins having especially desirable properties. Thus, the rubberycopolymer of one or more butadiene compounds and a mixture of theisomers of dichlorostyrene has properties in several respects superiorto those of natural rubber for tire treads and the like. Thedichlorostyrenes are somewhat disadvantageous, however, in that theytend to homopolymerize with exceedingly great rapidity. This factnecessitates the use of a substantial amount of inhibitor during theirpreparation and storage; it also requires that they be stored atrelatively low temperature at all times prior to use. The result of thisextreme activity toward polymerization renders their preparation and thepreparation of copolymerization products relatively more expensive thanwould otherwise be the case.

Itis found that the 2-(halophenyl), propenes that have, a plurality ofhalogen atoms in the nucleus, like Z-(phenyl) propenes, have little, ifany, noticeable tendency for homopolymerization unless they also have ahalogen substituted for I one of the hydrogens of the terminal methylenegroup. Unlike Z-(phenyl) propene, however, the 2-( alkyl) 2-(polychlorophenyl) alkenes-l, such as the 2-(dichlorophenyl) propenes,having the propene group free of halogen, do not necessarilycopolymerize with other materials such as butadiene, vinyl chloride,dichlorostyrenes and the like. In fact, We have found that little if anyappreciable copolymerization with desirable mono-olefinic polymerizablemonomeric materials occurs in the case of polychlorophenyl propenes thatwere prepared in a manner analogous to the method commercially used forthe preparation of dichlorostyrene, i. e. by subjecting cumene (in placeof the ethyl benzene) successively to nuclear chlorination, toside-chain chlorination, and subsequent side-chain dehydrochlorination.

Such 2-(polychlorophenyl) propenes consist largely of isomers havingchlorine in the 2 and/or 6 nuclear positions i. e. adjacent the nuclearcarbon atom carrying the unsaturated side-chain (alkylenyl group) It maybe that they are thereby so sterically or otherwise hindered by thelarge chlorine atom on the ortho carbon that copolymerization as well aspolymerization is prevented when methods analogous to those usually usedfor polymerization of unsaturated materials are relied on. In any event,we have been unable to polymerize or copolymerize these materials withpolymerizable' mono-olefinic monomeric materials to obtain desirableproducts, even though catalysts normally considered as suitable forinitiating emulsion and mass polymerization at ordinary temperaturesare.v present.

In our prior application Serial No. 667,728, now abandoned, We pointedout that the alpha-alkylstyrenes, 2- (polyhalophenyl) -2(all yl)alkylenes- 1, such as 2-(polychlorophenyl) propenes, which have aplurality of halogen atoms in the nucleus but which are free ofsubstituents on the carbon atoms next adjacent the carbon atom to whichthe olefin group is directly connected, copolymerize with suitablemono-olefinic monomers, such as styrene, acrylonitrile, etc. to formresinous materials having especially desirable properties for manyapplications. Such p'olyhalogenated alpha- -alkylstyrenes are also'iou'nd to have little tendency to form polymers by themselves(homopolymerize) and, therefore, still retain the advantage ofpermitting storage for substantial periods of time without the usualinhibitors. 5

They may be prepared "by any suitable process, as for example by thealkylati-on by propene of an orthodihalobenzene, such asorthodichlorobenzene, and subsequent dehydrogenation of the alkylatedproduct to yield 2-(3,4-dichlorophenyl) propene. By using higherhoinologues than propene for alkylation of the halogenated benzene,other alpha-alkylstyrenes halogenated in the nucleus may be prepared.The 2-(alkyl)" 2- (polyhaloaryl) ethylenes, i. e. 'polyhalogenatedalpha-alkylstyrenes used in the practice of the present invention,should for best results be substantially free of Z-(alkyl)2-(chlorophenyl) ethylenes having chlorine on the 2- and/or 6- positionsof the nucleus as these materials have a strong tendency to remainunpolymerized in the product. Such'unpolymerizable 2-(alkyl)Z-(chlorophenyl) ethylenes may, however, be

present to remain as a plasticizer when they are compatible with thefinal resin. Generally, it is preferred that they do not substantiallyexceed 25 or 30% of the total amount of polymerizable nuclearlyhalogenated phenylalkylenes. When, however, the polymerization orcopolymerization is accomplished by the use of such stron catalysts asthose of theFriedel-Crafts type, say an aluminum chloride-carbonbisulfide or aluminum chloride-ethylene dichloride complex, at lowtemperatures, such as below 40 0., even substantial amounts of theisopropenylchlorobenzenes having one, two or three chlorine atoms and,having-chlorine" on the number- Z- and/or .num ber fi-nuclearcarbonatoms; appear to polymerize and copolymerize to form useful liquidand 7 solid products.

Examples of suitable Friedele-Gra-fts catalysts that may be used arethosetsetiforthtin'the article entitled Friedel-Crafts Synthesis by N.O. Galloway, printed in Chemical Review,.vol. XVII, No. 3, 1935, page375. ChemicalReview ispubllshed by the American Chemical .Society in[Baltimore.

In our aforementioned prior application, it was pointed out that thepreferred polymerizable comonomers for copolymerization withtheaforementioned 2- (alkyl) 2- (polyhalophenyl) ethylenes, such as the2-(polyhalophenyl) pro- ...penes. contain. a yinyl .group C=C in which..:not,.in. excess of two. ,of the four free valences are directly.connected to. the equivalent number .rof..activating.groupsselected fromgroups such ..i for. example as phenyl..cyano,,substituted phenyL; nhalogen .etc.. and the remainingwalences are-con- ...nected .to.hydrogenand or galkyl.

It.has-.now been foundthat especially desirable polymerization. productsmay. also be produced by copolymerizingloneor.more of the aforemene:Wtioned -2- (all-';yl) 2' -,(p,olyhalophenyl) ,ethylenes, :having thenuclear carbon .atomsnext adjacent ...that.carbon atom directlycarryingthe. -alkylenyl rs roup.ifree. .of large-halogenesuch as .chlorine.Lilargeldhlorine isIIdisting'uished-tfromi the ,smau Lfinori-nelwhichmaylbe present). with unsaturated ethyle'nic..compounds..(compouhdscontaining. the vinylflgroup' C-:-C containing one or, imore I.fluorine atoms attached directly.to, the ethylenic mca-rboneven-.thoughias many as twowalences ;aremdirectly. connected.toadditional activating groups. such; for..., example ,as .-ICN, +COOR',(where. R is 11'ydrogen,,-al-kyl,. substituted ;alkyl or .amaminoigroup) acid. anhydride halogenated aryl (especially halogenatedfphenyl, -eincludingn all: of ethe 4 :isomers 1 of r --.-.GsH3Cl2,-+G6H2Cl3, -Ctl-lsFz etc.) andhalogen groups (in- -;-cluding-F;- C1,;Br: and evenl) Thus'cornpounds :ssuch as; tetrafluorethylene;symmetrical :and unqgsymmetrical s dichlorodifiuoro'ethyleneandtricfiuoromonochloroethylene;i etc; and compounds r :hsving one:,-tothree rvfiuori-ne atoms attacheddiififidtly to:-the:vinyl grouprand thefourth valence -;J:attaclied to a-groupwselected from hydrogen, :zalkyl;phenyl,"halogenatedphenyl; -cyanide;ether e-rand' carbonyloxy:groups-walso- :copolymerize unrzderalsuitable'conditions withthertaforementioned isopropenyl benzeneshaving a plurality of halo- --z:.gen .z'atomsi but having :thenuclear positions 2 .and (thee of :largehalogen.- Of these,.- the com- :poundshavina four-halogen atoms attached:to :the1vinyl;groumvtwoetofour. :of which halogens :are ,:fluorine, areusually preferred. -r. --Gompounds mhaving amore thanoneidonoregroup.suchas aryl, n1 alkyl'; .oxyalkyl, and

-;iCOR

Ugroups and particularly compounds having two flwsuchgroups'attached toone :carbonxofl-the vinyl 1 group,.usuallycopolymerize with theaforemenmtioned Z-(polyhalophenyl) 1r propenes with rgreaa.

est difficulty hence it is generally desirable that the copolymerizablematerials be further characterised by having no more than one suchdonorgroup directly attached to any one carbon atom. it has-also beenfound that even ethylene may, under suitable'conditions, becopolymerized with the 2-(3,4- or 3,5-dich1orophenyl) propenes with '"orwithout additional unsaturated monomeric :materials. :--:Thus, 1when themixture of the one .ormore 25('poly)1'or Z-(dichlorophenyl) propenes andethylene having any desired proportion of component monomers, forexample ethylene and the aforementioned polymerizable2(polychlorovphenyl)propene-proportioned within the range of 1 to 20orl20;to l and a pressure of at least 200 (preferably 1,000 or more)atmospheres is -'Fiitilizd-in conjunction with water to provide aninterfacial region for polymerization initiation and asuitable catalystsuch as around .2 to 5% of benzoyl peroxide,LtrimethyLa-mine oxide, orother trialkylamine oxide .-etc...and.an. exclusion orzabsencejofatmospheric. oxygen, adesirable solid, polymer .is .formed. at elevated..temperatures such as around 100 C. (50 to'l50fC.) .in a few-hours. One.ornnore othercomonomers .aslthe above mentioned fluoride containingcomonmers and/or other. unsaturated polymerizablematerials, such forexample as any "of those mentioned in ouraforementioned priorapplication, may also be present toovary the properties ;of.theicopolymer. The amount Lof anyconju- .gated diene, however,desirablein. resinous compositions is generallynot ;in,..excess iof .byweightfofthe polymerizable ingredients although as. muchas, 40 or evenmay. bepresent in ,someinstances.

The 2 .(3-,4-. .or, 3,5-dihalophehyl). .propenesiare lespecially.desirable. for- .copolymerization with the .ethylenic compounds. whichare. subjected to relatively .close .packing, .for. example tetrafiuor--,ethylene. andthelike. l A..small percentagegives increasedcompatibility withplastioizers without greatly ,.,deterioratingf theexcellent. electrical properties normally .presentin the closely packedpolyethylenic compounds. 'l2hus,. even. a. .rela-....tively.small.amount,- such-as I 1 or so, of- 2e (3,4- .-or,3,5.-.dihalophenyl) propenes has a noticeable effect onuthe propertiesof the copolymerization products, particularly those in. theacaseof themonomers of the ethylenictype subject to close packing, suchas may behad when only fluorine .land/orhydrogen atoms are presenton theethaylenic carbonatoms. -It is .usually preferredto haveatrleast 5. to10.- percentofthe aforementioned .dihalopropenes present however.

.lnasmuch as. the: 2-(3,4- and ,3,5 =dichloro- .phenyl) -propenes:homopolyrnerize with considerabledifiiculty unless a catalyst of the:Friedel- Crafts type is present, it, is generally preferable toutilize-aboutSO-or .60. mol percentor lessof thesematerials inpreparing-thecopolymers of the present invention. As muchas 90.or.95.mol percent may-be utilized, iisthe copolymerization isaccomplished at .very high :pressure or. in the presence of a strongcatalyst. capable. ofacausing homopolymer-izationor if .theexcess above50.mol

, --.per cent is desired as a .plasticizer. or. solvent.

The polymerization may be carried-=out-en masse,- with or withouttheadditionof a solvent ondiluent or with or without theaidof asuitablepolymerization catalyst. Either polymerization :en masse or 'the-so-called fpearlforlsuspension polymerization wherein the mixtureofpolymerizable materials, with or without a suitable cata- '76,, lystsuch asbenzoyl peroxideeta, is stronglyiagitated in water or in anaqueous solution ofa water-soluble resinous polymer such aspolymethacrylamide, polymethacrylic acid, polymethylvinyl ether,polyvinyl alcohol and the like is ordinarily preferred when a finelydivided clear resin suitable as a molding powder is desired. When one ofthe materials is water-insoluble and the others are readily soluble,mass polymerization in absence of water is preferred. If a clear resinis not necessary, we prefer to utilize emulsion polymerization, whereinthe mixture of polymerizable materials is incorporated in an aqueoussolution or suspension of emulsifying agent or protective colloid.Pigments, plasticizers and the like may be present during thepolymerization.

The emulsifying agents may be cationic (usually quaternary) ammoniumcompounds or anionic types. Examples of suitable emulsifying agentswhich may be used are set forth in the lists of surface-active agentscompiled by F, J. Van Antwerpen, published in Industrial and EngineeringChemistry, January 1939, pages 66 to 69; January 1941, pages 16 to 22;and January 1943, pages 126 to 130.

Suitable activators, such as complex salts of cobalt, particularlyalkali metal cobaltinitrites and alkali metal aquo hydroxylo nitritocobaltiates, in conjunction with a mercaptan such as dodecyl mercaptan,as set forth in patent application of John C. Warner and Harry Seltz,Serial No. 577,328, filed February 10, 1945, as well as other activatorsfor emulsion polymerization may be used. Emulsion polymerization usuallyyields products of higher molecular weight than does masspolymerization.

When one or more of the monomeric materials for copolymerization withthe 2-(3,4- or 3,5-dichlorophenyl) propenes is a relatively low boilinggas such as ethylene or the highly fiuorinated materials consisting ofhydrogen, carbon and halogen, polymerization at exceptionally highpressure, such as above 50 atmospheres and preferably in theneighborhood of about 500 or 1,000 to 3,000 atmospheres, is desirable toobtain sufficient speed. Such polymerization is usually accelerated byeliminating the air from the reactor and maintaining at least some waterand a suitable oxidizing catalyst as used for the homopolymerization ofethylene. A temperature around 100 C. as aforementioned or between 50 to200 or 250 C. is usually desired.

The finely divided resinous compositions of the present invention may bemolded directly from their latex or coagulated solid form or the solidsmay be ground or mixed with a plasticizer and/or solvent (capable ofcombining therewith at elevated temperature) to form a slurry which maybe used as a coating or molding composition, etc., and the thus coatedmaterial subjected to heat to cause coalescence of the solid particlesand compatibility with plasticizer andremaining solvent. Thesecompositions like others may, for example, be ball mill ground in thepresence of a plasticizer which is compatible at non-destructiveelevated temperatures, preferably diluted with a solvent or thinner suchas a drying oil, a hydrocarbon liquid such as kerosene, etc., and usedas a coating or dippin composition. If a dispersing agent such as one ormore watersoluble soaps, long chain amines, ink lengthener, is present(preferably during part of the grinding operation), a more flowableslurry or dispersion of finely divided resin is produced in saidplasticizer. Hot metal articles (heated above 250 C.) dipped into such adispersion retain relatively heavy layers thereon. After drying andheating the thus coated article to a temperature of about 300 0., orsufficiently to coalesce the dispersed particles, a coherent protectivefilm of surprising strength may be had over the surface of the metal.

The following examples, in which parts are by weight, illustrate thepresent invention:

Example 1 Parts 2-(3,4-dichlorophenyl) propene 65 Unsymmetricaldifiuorodichloroethylene 35 Water 200 Benzoyl peroxide .2

The above materials are charged in a silverlined high pressure autoclaveand agitated at about C. for about ten hours. At the end of the time theautoclave is opened and the product is removed, filtered, washed anddried. The finely divided polymer may be used as a molding powder and itmay be dissolved in solvent to form a suitable coating composition. Whenmixed with monomeric 2-(3A- or 3,5-dichlorophenyl) propene or when mixedwith styrene, the product may be used as a contact laminating resin.

Example 2 Parts 2-(3,4-dichlorophenyl) propene 50 Symmetricaldifiuorodichloroethylene 50 The above materials are substituted for thepolymerizable materials of Example 1, other conditions remaining thesame. The product has desirable properties for use as a molding powder.

Example 3 A silver-lined reaction vessel which has been purged of oxygenis charged with 200 parts of water, .2 part of benzoyl peroxide andabout 50 parts of 2-(3,4-dichlorophenyl) propene. It is then agitatedand pressurized with ethylene at about 1500 atmospheres pressurewhilethe autoclave is maintained at a temperature of about C. Afterabout ten hours, the reaction product is removed from the vessel, Washedand filtered. The polymer is soluble in aromatic solvents and hasdesirable electrical properties.

Example 4 Example 5 Parts 2- (3,4-dichlorophenyl) propene 10 Ethylene 90Butadiene 5 Water 200 Trimethylamine oxide hydrate 0.25

The Water which was purged of oxygen, together with the catalyst,.isincorporated into a stainless steel-lined high pressure reaction .vessel equipped for agitation and the 2-(3,4-dichlorophenyl) propene,ethylene and butadiene, then incorporated. The size of the vessel issuch that the pressure is maintained for at least five hours at 1,000atmospheres and preferably 1,500 to 3,00flatm'osphereswhilethetemperature is main tained around 100to 150 C. Extra ethylene may beadded when rtheipressure falls below 1,000 atmospheres. The polymerwhich, after eight to ten hours, :is removed from the reaction vessel,Washed and filtered, is heat softenable but less soluble in organicsolvents than the polymer of Example 3, due to perhaps the cross linkingof theconjugated butadiene compound.

Example 6 When in Example 4 the 2-(3,4-dich1orophenyl) propane isreduced to only 5 parts, a polymer is obtained having properties quitesimilar to polytetrafluoroethylene but which is substantially morecompatible with solvent and plasticizer. The polymer obtained still hasexceptionally desirable electrical properties and is suitable forinsulation in electrical apparatus.

Asmall amount of 2- (3,4-dichlorophenyl) propene apparentlyacts toseparate the molecules of the polymer sufficiently to permit greatercompatibility with plasticizers and solvents.

In the preceding examples the tetrafluoroethylene maybe substituted bytrifiuoroethylene, trifiuoromonochloroethylene, l-methyl-, 2,2difiuor-oethylene, allylene difiuoride, allyl esters such asallylfluoride, or l-(fluoro) 2-(3,i-dichlorophenyl) propane-1, etc. togive solid polymers which also have exceptionally desirable properties.Similarly, the 3,4-dichlorophenyl propylene in the above example may besubstituted in whole or in part'by 2-(3,5-dichlorophenyl) propene or bycorresponding fluorine, bromine or iodine derivatives. Compoundscontaining a plurality of separated unsaturated carbon-to-carbon link.-ages, such as double or even triple bonds, may also be present in thecompositions of the present invention to give a cross linking thatmodifies the heat softening point of the resinous materials produced.These compounds are herein termed polyene compounds and should bepresent in amounts of substantially less than 45 per cent of the totalpolymerizable constituents and only small amounts such as less than orpercent are ordinarily desired. Oi the polyene compounds, thebutadienecompounds which contain conjugated double bonds such as butadiene,isoprene, l-cyano of 2-cyano butadiene-l,3, piperylene, 'haloprenes suchas chloroprene, fluoroprene, and other conjugated dienes having lessthan eight carbon atoms in a Single chain are ordinarily used because oflower cost or greater availability. The butadiene in Example 5 may besubstituted by other butadiene compounds or by other polyenes havingcarbon-to-carbon unsaturated linkages in nonconjugated relationship tovary the softening points and solubility.

In the above examples, one or more additional monomeric materials suchas acrylonitrile, vinyl chloride, vinylidene chloride, styrene or otherunsaturated polymerizable monomeric material, as described in ouraforementioned prior application, may also be present in thepolymerizable mixture to vary the properties of the resultant polymer.

As aforementioned, our prior application Serial No. 667,728, filed May6, 1946, is directed to copolymers of polychloro-alpha-alkylstyreneswith a copolymerizable mono-olefinic compound having an olefinic groupactivated or in conjugated relation to a carbon atom havingat'least twovalences thereof satisfied by a single atom. This and other subjectmatter disclosed and not claimed herein is claimed in this copendingapplication.

It is'apparent that modifications of the invention may be made withoutdeparting from the spirit thereof and it is intended that the inventionbe limited only by the appended claims;

What we claim is:

1. A 'copolymerization product of an alphamethylstyrene and a member ofthe group consisting of ethylene and ethylenes having one to fourhydrogen atoms substituted by fluorine, said 'alpha-methylstyrene havingtWo nuclear halogen atoms and having nuclear carbon atoms next adjacentthecarbon atom directly carrying the isopropenyl group free ofsubstituentsthe amount of alpha-methylstyrene having the abovecharacteristics being 1 to 90 mol per cent of said copolymerizationproduct.

2. A copolymerization product of 3,4-dichloro alpha-methylstyrene and anethylene having one to four hydrogen atoms substituted by fluorine, saidSA-dichloro alpha methylstyrene being present in amounts of '1 to 90 molpercent.

3. A copolymerization product of 3,4-dichloroalpha-methylstyrene and anethylene having one to four hydrogen atoms substituted by fluorine, said3,4-dichloro alpha methylstyrene being present in amounts of 5 to 60 molpercent.

4. A copolymerization product of tetrafluoroethylene and3,4-dichloro-alpha-methylstyrene, said copolymerization product having 1to mol percent of said 3,4-dichloro-alpha-methy1styrene.

5. A copolymerization product of 3,4-dichloroalpha-methylstyrene anddifluorodichloroethylone, said 3,4-dichloro-a1pha-methylstyrene being 5to mol percent of said copolymerization product.

6. A copolymerization product of 3,4-dichloroalpha-methylstyrene and anunsymmetrical difluorodichloroethylene, said3,4-dichloro-alphamethylstyrene being 5 to 60 mol percent of saidcopolymerization product.

'7. A method of making a copolymerization product of analpha-methylstyrene having a plurality of nuclear halogen atoms, butwith the nuclear carbon atom next adjacent the carbon atom carrying theisopropenyl group free of substituents, and an ethylene having one tofour hydrogen atoms substituted by fluorine, the steps Which compriseincorporating said ethylene in the presence of water, a catalyst andsaid alphamethylstyrene in a pressure vessel, and maintaining them undera pressure of at least 50 atmospheres and at elevated temperatures untila solid polymer is formed, said alpha-methylstyrene being 1 to 60 molpercent of the monomeric materials.

THEODORE A. TE GROTENHUIS. GILBERT H. SWART.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number I Name Date 2,403,213 DAlelio July 2,19462,473,985 Brooks June 21, 1949

1. A COPOLYMERIZATION PRODUCT OF AN ALPHAMETHYLSTYRENE AND A MEMBER OFTHE GROUP CONSISTING OF ETHYLENE AND ETHYLENES HAVING ONE TO FOURHYDROGEN ATOMS SUBSTITUTED BY FLUORINE, SAID ALPHA-METHYLSTYRENE HAVINGTWO NUCLEAR HALOGEN ATOMS AND HAVING NUCLEAR CARBON ATOMS NEXT ADJACENTTHE CARBON ATOM DIRECTLY CARRYING THE ISOPROPENYL GROUP FREE OFSUBSTITUENTS, THE AMOUNT OF ALPHA-METHYLSTYRENE HAVING THE ABOVECHARACTERISTICS BEING 1 TO 90 MOL PER CENT OF SAID COPOLYMERIZATIONPRODUCT.